#region Apache License
//
// Licensed to the Apache Software Foundation (ASF) under one or more 
// contributor license agreements. See the NOTICE file distributed with
// this work for additional information regarding copyright ownership. 
// The ASF licenses this file to you under the Apache License, Version 2.0
// (the "License"); you may not use this file except in compliance with 
// the License. You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
//
#endregion

using System;

using log4net;
using log4net.Core;
using log4net.Util;

namespace log4net.Filter
{
    /// <summary>
    /// Simple filter to match a string in the event's logger name.
    /// </summary>
    /// <remarks>
    /// <para>
    /// The works very similar to the <see cref="LevelMatchFilter"/>. It admits two 
    /// options <see cref="LoggerToMatch"/> and <see cref="AcceptOnMatch"/>. If the 
    /// <see cref="LoggingEvent.LoggerName"/> of the <see cref="LoggingEvent"/> starts 
    /// with the value of the <see cref="LoggerToMatch"/> option, then the 
    /// <see cref="Decide"/> method returns <see cref="FilterDecision.Accept"/> in 
    /// case the <see cref="AcceptOnMatch"/> option value is set to <c>true</c>, 
    /// if it is <c>false</c> then <see cref="FilterDecision.Deny"/> is returned.
    /// </para>
    /// </remarks>
    /// <author>Daniel Cazzulino</author>
    public class LoggerMatchFilter : FilterSkeleton
    {
        #region Member Variables

        /// <summary>
        /// Flag to indicate the behavior when we have a match
        /// </summary>
        private bool m_acceptOnMatch = true;

        /// <summary>
        /// The logger name string to substring match against the event
        /// </summary>
        private string m_loggerToMatch;

        #endregion

        #region Constructors

        /// <summary>
        /// Default constructor
        /// </summary>
        public LoggerMatchFilter()
        {
        }

        #endregion

        #region Properties

        /// <summary>
        /// <see cref="FilterDecision.Accept"/> when matching <see cref="LoggerToMatch"/>
        /// </summary>
        /// <remarks>
        /// <para>
        /// The <see cref="AcceptOnMatch"/> property is a flag that determines
        /// the behavior when a matching <see cref="Level"/> is found. If the
        /// flag is set to true then the filter will <see cref="FilterDecision.Accept"/> the 
        /// logging event, otherwise it will <see cref="FilterDecision.Deny"/> the event.
        /// </para>
        /// <para>
        /// The default is <c>true</c> i.e. to <see cref="FilterDecision.Accept"/> the event.
        /// </para>
        /// </remarks>
        public bool AcceptOnMatch
        {
            get { return m_acceptOnMatch; }
            set { m_acceptOnMatch = value; }
        }

        /// <summary>
        /// The <see cref="LoggingEvent.LoggerName"/> that the filter will match
        /// </summary>
        /// <remarks>
        /// <para>
        /// This filter will attempt to match this value against logger name in
        /// the following way. The match will be done against the beginning of the
        /// logger name (using <see cref="M:String.StartsWith(string)"/>). The match is
        /// case sensitive. If a match is found then
        /// the result depends on the value of <see cref="AcceptOnMatch"/>.
        /// </para>
        /// </remarks>
        public string LoggerToMatch
        {
            get { return m_loggerToMatch; }
            set { m_loggerToMatch = value; }
        }

        #endregion

        #region Override implementation of FilterSkeleton

        /// <summary>
        /// Check if this filter should allow the event to be logged
        /// </summary>
        /// <param name="loggingEvent">the event being logged</param>
        /// <returns>see remarks</returns>
        /// <remarks>
        /// <para>
        /// The rendered message is matched against the <see cref="LoggerToMatch"/>.
        /// If the <see cref="LoggerToMatch"/> equals the beginning of 
        /// the incoming <see cref="LoggingEvent.LoggerName"/> (<see cref="M:String.StartsWith(string)"/>)
        /// then a match will have occurred. If no match occurs
        /// this function will return <see cref="FilterDecision.Neutral"/>
        /// allowing other filters to check the event. If a match occurs then
        /// the value of <see cref="AcceptOnMatch"/> is checked. If it is
        /// true then <see cref="FilterDecision.Accept"/> is returned otherwise
        /// <see cref="FilterDecision.Deny"/> is returned.
        /// </para>
        /// </remarks>
        override public FilterDecision Decide(LoggingEvent loggingEvent)
        {
            if (loggingEvent == null) {
                throw new ArgumentNullException("loggingEvent");
            }

            // Check if we have been setup to filter
            if ((m_loggerToMatch != null && m_loggerToMatch.Length != 0) &&
                loggingEvent.LoggerName.StartsWith(m_loggerToMatch)) {
                // we've got a match
                if (m_acceptOnMatch) {
                    return FilterDecision.Accept;
                }
                return FilterDecision.Deny;
            }
            else {
                // We cannot filter so allow the filter chain
                // to continue processing
                return FilterDecision.Neutral;
            }
        }

        #endregion
    }
}
